368 research outputs found

    Searching for a Leptophilic Z' and a 3-3-1 symmetry at CLIC

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    We derive the discovery potential of a leptophilic Z', and a Z' rising from a SU(3)×SU(3)L×U(1)NSU(3) \times SU(3)_L \times U(1)_N symmetry at the Compact Linear Collider (CLIC), which is planned to host e+ee^+e^- collisions with 3 TeV center-of-mass energy. We perform an optimized selection cut strategy on the transverse momentum, pseudorapidity, and invariant mass of the dileptons in order to enhance the collider sensitivity. We find that CLIC can potentially reach a 5σ5\sigma signal of a 131-3~TeV leptophilic Z' with less than 1fb11fb^{-1} of integrated luminosity. As for the Z' belonging to a 3-3-1 symmetry, CLIC will offer a complementary probe with the potential to impose MZ>3M_{Z^\prime} > 3~TeV with L=2fb1\mathcal{L}=2fb^{-1}.Comment: 8 pages, 4 figure

    Search for ultra-high energy photons through preshower effect with gamma-ray telescopes: Study of CTA-North efficiency

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    Indexación ScopusAs ultra-high energy photons (EeV and beyond) propagate from their sources of production to Earth, radiation-matter interactions can occur, leading to an effective screening of the incident flux. In this energy domain, photons can undergo e+/e− pair production when interacting with the surrounding geomagnetic field, which in turn can produce a cascade of electromagnetic particles called preshower. Such cascade can initiate air showers in the Earth's atmosphere that gamma-ray telescopes, such as the next-generation gamma-ray observatory Cherenkov Telescope Array, can detect through Cherenkov emission. In this paper, we study the feasibility of detecting such phenomenon using Monte-Carlo simulations of nearly horizontal air showers for the example of the La Palma site of the Cherenkov Telescope Array. We investigate the efficiency of multivariate analysis in correctly identifying preshower events initiated by 40 EeV photons and cosmic ray dominated background simulated in the energy range 10 TeV – 10 EeV. The effective areas for such kind of events are also investigated and event rate predictions related to different ultra-high energy photons production models are presented. While the expected number of preshowers from diffuse emission of UHE photons for 30 hours of observation is estimated around 3.3×10−5 based on the upper limits put by the Pierre Auger Observatory, this value is at the level of 2.7×10−4 (5.7×10−5) when considering the upper limits of the Pierre Auger Observatory (Telescope Array) on UHE photon point sources. However, UHE photon emission may undergo possible ”boosting” due to gamma-ray burst, increasing the expected number of preshower events up to 0.17 and yielding a minimum required flux of ~ 0.2 km−2yr−1 to obtain one preshower event, which is about a factor 10 higher than upper limits put by the Pierre Auger Observatory and Telescope Array (0.034 and 0.019 km−2yr−1, respectively). © 2020https://www-sciencedirect-com.recursosbiblioteca.unab.cl/science/article/pii/S092765052030061X?via%3Dihu

    Observation of Collider Muon Neutrinos with the SND@LHC Experiment

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    We report the direct observation of muon neutrino interactions with the SND@LHC detector at the Large Hadron Collider. A dataset of proton-proton collisions at √ s = 13.6 TeV collected by SND@LHC in 2022 is used, corresponding to an integrated luminosity of 36.8 fb − 1 . The search is based on information from the active electronic components of the SND@LHC detector, which covers the pseudorapidity region of 7.2 < η < 8.4 , inaccessible to the other experiments at the collider. Muon neutrino candidates are identified through their charged-current interaction topology, with a track propagating through the entire length of the muon detector. After selection cuts, 8 ν μ interaction candidate events remain with an estimated background of 0.086 events, yielding a significance of about 7 standard deviations for the observed ν μ signal

    SND@LHC: The Scattering and Neutrino Detector at the LHC

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    SND@LHC is a compact and stand-alone experiment designed to perform measurements with neutrinos produced at the LHC in the pseudo-rapidity region of 7.2<η<8.4{7.2 < \eta < 8.4}. The experiment is located 480 m downstream of the ATLAS interaction point, in the TI18 tunnel. The detector is composed of a hybrid system based on an 830 kg target made of tungsten plates, interleaved with emulsion and electronic trackers, also acting as an electromagnetic calorimeter, and followed by a hadronic calorimeter and a muon identification system. The detector is able to distinguish interactions of all three neutrino flavours, which allows probing the physics of heavy flavour production at the LHC in the very forward region. This region is of particular interest for future circular colliders and for very high energy astrophysical neutrino experiments. The detector is also able to search for the scattering of Feebly Interacting Particles. In its first phase, the detector will operate throughout LHC Run 3 and collect a total of 250 fb1\text{fb}^{-1}

    Studies of new Higgs boson interactions through nonresonant HH production in the b¯bγγ fnal state in pp collisions at √s = 13 TeV with the ATLAS detector

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    A search for nonresonant Higgs boson pair production in the b ¯bγγ fnal state is performed using 140 fb−1 of proton-proton collisions at a centre-of-mass energy of 13 TeV recorded by the ATLAS detector at the CERN Large Hadron Collider. This analysis supersedes and expands upon the previous nonresonant ATLAS results in this fnal state based on the same data sample. The analysis strategy is optimised to probe anomalous values not only of the Higgs (H) boson self-coupling modifer κλ but also of the quartic HHV V (V = W, Z) coupling modifer κ2V . No signifcant excess above the expected background from Standard Model processes is observed. An observed upper limit µHH &lt; 4.0 is set at 95% confdence level on the Higgs boson pair production cross-section normalised to its Standard Model prediction. The 95% confdence intervals for the coupling modifers are −1.4 &lt; κλ &lt; 6.9 and −0.5 &lt; κ2V &lt; 2.7, assuming all other Higgs boson couplings except the one under study are fxed to the Standard Model predictions. The results are interpreted in the Standard Model efective feld theory and Higgs efective feld theory frameworks in terms of constraints on the couplings of anomalous Higgs boson (self-)interactions
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